Work-Function Engineering of Graphene Electrodes by Self-Assembled Monolayers for High-Performance Organic Field-Effect Transistors

Abstract

We have devised a method to optimize the performance of organic field-effect transistors (OFETs) by controlling the work functions of graphene electrodes by functionalizing the surface of SiO2 substrates with self-assembled monolayers (SAMs). The electron-donating NH2-terminated SAMs induce strong n-doping in graphene, whereas the CH3-terminated SAMs neutralize the p-doping induced by SiO2 substrates, resulting in considerable changes in the work functions of graphene electrodes. This approach was successfully utilized to optimize electrical properties of graphene field-effect transistors and organic electronic devices using graphene electrodes. Considering the patternability and robustness of SAMs, this method would find numerous applications in graphene-based organic electronics and optoelectronic devices such as organic light-emitting diodes and organic photovoltaic devices.

Electronic structure of MoO3−x/graphene interface

“…Abundant results have shown that large E F shift of graphene from its E D could be realized by surface doping depending on the electron affinity and coverage of the surface adsorbate [44,45]. Change of graphene charge carrier concentration (electron or hole) due to the surface doping has been detected [38].…”

Contact engineering in organic field-effect transistors

“…3d), for example, -NH 2 decreases w m , whereas -F and -CN increase w m [66]. Note that the effects of increasing/decreasing w m are similar when casting the same SAM on different metals, for example, Au, Ag [54,67,68], Cu [69], Pt [70], ITO [71], and so on, as well as on nonmetal contacts (e.g., graphene) [72].…”

Photochemical stability and reactivity of graphene oxide

“…oxidized moieties such as in GO) generates a band gap, opening its applicability in functional nanoelectronic devices. [24,25] The quenching of the fluorescence emission with the increment of the oxidation degree is related with the increase of the density of localized states that, as for the semiconductor, can force the dissipation energy processes toward non radiative paths (e.g. vibrational relaxation).…”